The present invention is directed to a method and apparatus for the automatic monitoring of textile fabrics, especially woven fabrics, in which the woven fabric is continuously scanned by an electrical-optical device immediately at the weaving machine or at a cloth rolling machine located separate from the weaving machine, and defective variations from the texture judged to be normal are detected and displayed.
The present practice in weaving establishments is to examine cloth on cloth inspection tables or cloth inspection machines, in which the cloth is passed over a flat inspection board or over a curved inspection table, and the cloth is visually examined with the aid of illumination from a source built into the inspection board or inspection table. Proposals have already been made for the automation of the arduous inspection duties of the operator by using sensor systems, such as scanning cameras, plane cameras or laser scanners, but because of the costs involved, these sensor systems are typically suited only for one type of cloth inspection table. A common feature of these two types of monitoring systems is that they are used away from the weaving machine and often are employed a relatively long time after the weaving process has veen completed.
When inspecting the fabric, the operator not only has to examine the cloth, but where possible, has to remedy the faults which are detected, which in some cases takes place on special burling and mending tables. When it is not possible to remedy a fault, then the faulty portion must be cut out and at best the cloth can be sold only as second quality.
As it is a constant occurrence for fabrics to contain faults which could have been avoided by action being taken in the weaving process, it has already been often suggested that monitoring of the cloth should take place directly at the weaving machine, as then there would exist the possibility of taking corrective action.
Thus, it is known from U.S. Pat. No. 3,502,115 that an inspection station in the form of a cloth inspection table may be set up directly at the weaving machine, so that faults which could be remedied by modifying the setting of the weaving machine could be detected as early as possible. The required adjustments of the weaving machine could thus be quickly undertaken and the amount of second quality cloth could be reduced. However, when it is considered that the working conditions for operators in the weaving shed are significantly worse than those conditions which prevail in the cloth inspection room in which cloth examination usually takes place, then one would reach the conclusion that this type of cloth inspection will result in an increase rather than a reduction in second quality cloth. Apart from this, the trend in weaving is towards higher productivity. As the production speed of a weaving machine is appreciably lower than the cloth speed during cloth inspection, from this aspect the separation of the weaving process and cloth inspection is economically the more sensible solution. Therefore, this manner of relocation of cloth inspection to the weaving machine would typically be regarded technically as a backward step.
It is known from U.S. Pat. No. 3,613,743 that faults in a fabric may be detected optically by means of a detection apparatus mounted rigidly so as to be stationary on the weaving machine and in which the corresponding fault signals are stored cumulatively together with the length signals representing the length of the cloth. The fault signals are subsequently compared with reference data and a signal is produced when the stored cumulative fault signal exceeds a tolerable limit valve, or when the detected faults are determined to be difficult to remedy. This signal stops the weaving machine and actuates a mechanism for applying a cut mark at the selvedge and for illuminating a warning lamp.
As there is no indication of how the faults may be differentiated by type, i.e., whether they may or may not be repaired, it must be the basis of this known method that the faults per unit length are counted, and when a prescribed value is exceeded, the weaving machine is stopped. However, this results in an increase in the frequency of stoppages of the weaving machine and consequently to a reduction in efficiency without fabric quality being improved or any possibility of making any kind of savings in cloth inspection.